What does a filter bypass valve allow during a filter failure?

A filter bypass valve plays a critical role in maintaining the operation of an engine in the event of a filter failure. When the filter becomes clogged or fails, the bypass valve opens, allowing oil to flow around the filter instead of through it. This means that unfiltered oil can still reach the critical components, such as the bearings, to ensure they receive lubrication. While this situation is not ideal, as it allows contaminants to bypass filtration, it is essential for preventing complete oil starvation and potential engine failure. The primary function of the bypass valve is to protect the engine from damage by ensuring that lubrication continues, albeit with less protection against particles that could cause wear.